Recent activity

The geomagnetic field was quiet on April 9.
Solar
wind
speed ranged between 294 and 338 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 88.4. The planetary
A
index was 4 (STAR Ap - based on the mean of three hour interval ap
indices: 4.5).
Three hour interval K indices: 21011221 (planetary), 12112322 (Boulder).

The background x-ray flux is at the class A7 level.

At midnight there were 4 spotted regions on the visible solar disk.
The solar flare activity level was very low. No C class events were
recorded during the day.

Region 10749 decayed slowly and quietly.
Region 10750 decayed early in the day and lost all spots outside the main penumbral area. Moderate development was
observed late in the day with several new spots emerging and new penumbra forming. The region has mixed polarities. C flares are
possible.
Region 10751 developed slowly. The region is magnetically a mess with several small areas of positive and negative
polarity intermixing. C flares are possible.

Spotted regions not numbered by NOAA/SEC:[S533] This region emerged on April 9 in the northeast quadrant near the central meridian and inside CH157. Several
spots were visible at one point, however, the region was decaying slowly late in the day and only a single, small spot was visible
at midnight. Location at midnight: N19W02.

Coronal mass ejections (CMEs)

April 7-9: No obvious fully or partly Earth
directed CMEs
were observed.

Coronal holes

A recurrent coronal hole (CH157) in the northern hemisphere will be in an earth facing
position on April 9-10.

Processed SOHO/EIT 284 image at 01:06 UTC on April 10. The
darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet on April 10-11 and quiet to active on April 12-13 due to effects from CH157..

Coronal holes (1)

Coronal mass ejections (2)

M and X class flares (3)

1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next
48 hours.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation
along
east-west paths over high and upper middle latitudes is poor to fair.
Propagation along long distance north-south paths is poor.
Trans
Atlantic propagation conditions are normally monitored every night on
1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). The best reception from North America was of CJYQ 930, VOWR 800
and KNR on 650 kHz, all with fair signals.

Data for all numbered solar regions according to the Solar Region
Summary provided by
NOAA/SEC. Comments are my own, as is the
STAR spot count (spots observed at or inside a few hours before
midnight) and data for regions not numbered by SEC or where SEC has
observed no spots.
SEC active region numbers in the table below and in the active region
map above are the historic
SEC/USAF numbers.

Active region

Date numbered

SEC
spot
count

STAR
spot
count

Location at midnight

Area

Classification

Comment

10748

2005.03.31

N11W57

plage

10749

2005.04.03

1

1

S05W17

0010

HSX

10750

2005.04.05

6

10

S07E24

0100

DAI

beta-gamma

10751

2005.04.08

6

5

S07W74

0080

DAI

beta-gamma
area was 0050 at midnight

S533

2005.04.09

1

N19W02

0010

AXX

Total spot count:

13

17

SSN:

43

57

Monthly solar cycle data

Month

Average solar
flux at Earth

International sunspot number

Smoothed sunspot number

2000.04

184.2

125.5

120.8
cycle 23 sunspot max.

2000.07

202.3

170.1

119.8

2001.12

235.1

132.2

114.6 (-0.9)

2004.02

107.0

45.8

49.3 (-2.7)

2004.03

112.0

49.1

47.1 (-2.2)

2004.04

101.2

39.3

45.5 (-1.6)

2004.05

99.8

41.5

43.8 (-1.7)

2004.06

97.4

43.2

41.6 (-2.2)

2004.07

119.1

51.1

40.2 (-1.4)

2004.08

109.6

40.9

39.2 (-1.0)

2004.09

103.1

27.7

37.5 (-1.7)

2004.10

105.9

48.0

(35.6 predicted, -1.9)

2004.11

113.2

43.5

(33.9 predicted, -1.7)

2004.12

94.5

17.9

(31.6 predicted, -2.3)

2005.01

102.2

31.3

(28.9 predicted, -2.7)

2005.02

97.2

29.1

(26.5 predicted, -2.4)

2005.03

89.9

24.8

(24.7 predicted, -1.8)

2005.04

85.0 (1)

13.4 (2)

(22.9 predicted, -1.8)

1) Running average based on the daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC)
sunspot number. The official international sunspot number is typically
30-50% less.

This report has been prepared by Jan
Alvestad. It is based partly on my own observations and analysis,
and
partly on data from some of these solar data sources.
All time references are to the UTC day. Comments and suggestions are
always welcome.